1. Field of the Invention
The invention relates to a sample manipulation device, which comprises an observation unit, which is used to observe a sample and to select a predetermined position at which a sample portion to be removed is located, as well as a specimen stage which receives the sample. The invention relates to difficulties in handling which occur when a sample is being observed while simultaneously carrying out manipulations on the sample which are monitored via the observation unit.
2. Background
In medical, biological and biochemical research, problems involving experiments with individual cells are gaining more and more importance. An important example thereof is the analysis and clarification of molecular regulating mechanisms or so-called molecule cascades. For this purpose, the cell of interest is detached from the cell array and transferred to a nutrient solution which is suitable to keep the cell alive. If conditions are favorable, the initial cell reproduces until sufficient material for the intended analytical method is present; so-called cell lines are prepared. A considerable disadvantage of the method of preparing cell lines is that the starting cell and the cells descending from this cell encounter idealized environmental conditions. However, analytical results obtained in this way do not represent the conditions actually present in the organism.
Neurobiological problems, too, can not be resolved, or resolved only insufficiently, in this manner. For example, after a certain period of time, a neuron isolated from a network of neuronal cells no longer represents that cell which it formerly represented when a part of the neural network. Presently no method is known by which the state of the cell within the network can be preserved with simultaneous reproduction.
On the other hand, biochemical problems can be addressed if sensitive analytical methods are used for which small amounts of material—in particular individual cells—are sufficient. This requires individual cells to be removed from the sample and transferred to an analyzing apparatus within a certain time. This is the only way to ensure that degradation processes within cells have not decomposed the substances to be examined and requires specific removal of an individual, identified, selected cell. One possibility of identification is the utilization of morphologic differences which can be determined by means of microscopy. Another possibility of identification consists in the use of dyes. These dyes can be visualized by fluorescence microscopy and thus enable identification of those cells which are marked with this dye.
In the prior art, there are presently several possibilities of removing individual cells from a sample. One method involves manual preparation, during which the experimenter observes the sample through a stereo microscope and removes individual cells from the sample by mechanical tools. However, this method is complex, time-consuming, and requires the experimenter to have an above average dexterity which is usually acquired only after many years. Another possibility of preparation consists in microdissection, in which UV lasers, for example, are used for cutting. However, this type of preparation requires tissue sections which do not represent living cells. Moreover, inverted microscopes must be used, i.e., the required manual preparation, on the one hand, and the observation, on the other hand, are effected from opposite directions towards the specimen. Although this can be avoided by consecutively using a stereo microscope, then an inverted microscope. The latter method is highly prone to error, due to the continually repeated changing of the microscopes.